1. Technical Field
The present invention relates to an atom cell, a quantum interference device, an atomic oscillator, an electronic apparatus, and a moving object.
2. Related Art
Atomic oscillators that oscillate based on an energy transition of alkali metal atoms including rubidium and cesium are known for having high-accuracy oscillation characteristics on a long-term basis.
Generally, the operation principle of atomic oscillators is roughly classified into a system using a double resonance phenomenon by light and microwave and a system using a quantum interference effect (CPT: Coherent Population Trapping) by two kinds of lights having different wavelengths.
Typically, in either atomic oscillator system an alkali metal is entrapped within a gas cell (atom cell) and the gas cell is heated to a predetermined temperature by a heater so that the alkali metal may be kept in a fixed gas condition.
Here, generally, not all of the alkali metal within the gas cell is gasified, but part of the metal is liquefied as an excess. The excessive alkali metal atoms are liquefied by precipitation (condensation) in a part of the gas cell at a lower temperature. If the liquid exists in a region in which excitation light passes, the liquid blocks the excitation light and, as a result, causes degradation of the oscillation characteristics of the atomic oscillator.
Accordingly, in a gas cell according to JP-A-2010-205875, a recessed part for precipitation of the alkali metal is provided on the inner wall surface of the gas cell.
However, in the gas cell according to JP-A-2010-205875, the excessive alkali metal precipitated within the recessed part faces the passage region of the excitation light and part of the excited gaseous alkali metal comes into contact with the excessive alkali metal within the recessed part, and thereby, the condition of the excited gaseous alkali metal becomes inhomogeneous. As a result, a problem of degradation of the oscillation characteristics (e.g., frequency fluctuations) occurs.